The present invention relates to a piston-cylinder assembly for brakes. Ceramic pistons for the actuation of brakes are known as used on wheel brake cylinders. German printed and published patent application DE-OS 16 55 344, for instance, discloses an arrangement of one known type. In this known arrangement, the piston for the wheel brake cylinder is made entirely from any ceramic material, e.g. magnesium silicate or aluminium oxide. Arranged in front of the piston in the pressure chamber is a primary seal and a filler consisting of plastics. A piston comprising a ceramic pressure member is known from German printed and published patent application DE-OS 31 48 873.
Principally, such ceramic pistons afford a great number of advantages, such as low-cost manufacture; configuration in a number of minor shape variations, dimensional stability even at higher temperatures resulting no change in the clearance between piston and cylinder bore; poor heat conduction as a result of which the hydraulic system is protected against becoming overheated; resistance to compression, corrosion resistance as a result of which jamming of the pistons due to corrosion is prevented; noise-damping effect and low weight.
However, sealing problems occur with the known arrangements, in particular upon the occurrence of major dimensional discrepancies in the manufacture of the ceramic components.